Watermarked material processing

ABSTRACT

A material (e.g. video, audio or data) processing system ( 648 ) processes material including a watermark. The system comprises a remover ( 640 ) for removing the watermark, a processor ( 646 ) for processing the material from which the watermark has been removed, and an inserter ( 642 ) for inserting a watermark into the processed material.

[0001] The present invention relates to a system and method forprocessing material. The material may be one or more of video material,audio material, and data material other than video and/or audio. Thusmaterial is represented by an information signal, which preferably is adigital signal.

[0002] It is known to use watermarks in material for example videomaterial to indicate the provenance of the material. However someprocessing may damage or destroy a watermark.

[0003] According to a first aspect of the present invention, there isprovided a processing system for processing material including awatermark, the system comprising a remover for removing the watermark, aprocessor for processing the material from which the watermark has beenremoved, and an inserter for inserting a watermark into the processedmaterial.

[0004] Thus the watermark is removed before processing and a watermarkis inserted after processing, avoiding damage to a watermark. Thewatermark inserted after processing may be the same as the removedwatermark or may be different.

[0005] In principle such a system could be under the control of a userof the processor. However, if the user can control the removal andinsertion process, he could indulge in fraud. Thus to prevent fraud theremoval and insertion process is preferably automatic and independent ofthe user. Most preferably it is performed without the knowledge of theuser. Thus the material processing system is closed with respect to theremoval and insertion of watermarks.

[0006] The removal and insertion of watermark may involve the use ofdata enabling those processes. Preferably, the enabling data is anencryption key. The enabling data may be securely stored or generated inthe processor. Alternatively, the enabling data may be stored in andretrieved from a separate, preferably secure, database. The database maybe linked, e.g. via a suitable communications link, to the system.Preferably, the link provides secure transfer of the enabling data.

[0007] According to a second aspect of the invention, there is provideda method of processing material including a watermark, comprising thesteps of: removing the watermark; processing the material from which thewatermark has been removed using a processor; and inserting a watermarkinto the processed material.

[0008] According to a third aspect of the invention, there is provided amethod of removing data embedded in material comprising the steps of:receiving material in which data is embedded; accessing an informationstore storing information enabling the data to be removed; and removingthe said data using the enabling data accessed from the store.

[0009] According to a fourth aspect of the invention, there is provideda method comprising the steps of: embedding data in material; andstoring, in an information store, information for enabling the data tobe removed from the material.

[0010] According to a fifth aspect of the invention, there is providedapparatus for removing data embedded in material comprising: an inputfor receiving material in which data is embedded; an information storefor storing information enabling the data to be removed; and a removerarranged to remove the said data using the enabling data accessed fromthe store.

[0011] According to a sixth aspect of the invention, there is providedapparatus comprising: an embedder for embedding data in material; astore for storing information for enabling the data to be removed fromthe material.

[0012] For a better understanding of the present invention, there willnow be described, by way of example, an illustrative embodiment of theinvention with reference to the accompanying drawings, in which:

[0013]FIG. 1 is a schematic block diagram of an illustrative watermarkinsertion and removal system;

[0014]FIGS. 2 and 3 are schematic diagrams of data structures of UMIDsFIG. 4 is a schematic block diagram an illustrative data structure of ametadata base;

[0015]FIGS. 5 and 6 are schematic diagrams of watermarking insertiontechniques;

[0016] and

[0017]FIG. 7 is a schematic diagram of a watermarking removal technique.

[0018] The following description illustrates the invention by way ofreference to video material. However, the invention is not limited tovideo material.

[0019] Overview-FIG. 1

[0020] Referring to FIG. 1, a video processing system 648 processesvideo material input at input 632 and outputs processed video at output630. The system 648 includes a processor 646 which may be an editor, aspecial effects machine, a mixer or any other video processor. Whilstonly one input and one output is shown, the processing system and theprocessor 646 may have a plurality of inputs and at least one output. Ifthe processor 646 is a mixer for example it has two or more inputs.

[0021] The processor 646 has a user interface 644 having user controls(not shown) for controlling the processor 646.

[0022] The input material contains watermarks. Watermarks are describedin the section watermarks below. Watermarks may be used to check theprovenance of video material. Watermarks may identify the owners of thematerial. In a preferred embodiment of the invention, the watermarksidentify the material (which we believe to be a novel idea). Mostpreferably the watermarks are based on UMIDs (which we believe to be anovel idea). UMIDs are described in the section UMIDs below.

[0023] In accordance with a preferred embodiment of the presentinvention, the processing system 648 is a closed system with respect toprocessing watermarks. That is the user has control only of the videoprocessor 646 but no control of, nor access to, the watermarkprocessing. The watermark processing is automatic and invisible to theuser. In a preferred embodiment as shown in FIG. 1, system 648 is anintegral unit comprising the remover 640, the processor 646, theinserter 642 and the contoller 638.

[0024] Thus in accordance with the present embodiment, watermarks of thematerial received at the input 632 (referred to herein as “inputwatermarks”) are automatically removed in a remover 640 before videoprocessing in the processor 646, and watermarks are automaticallyinserted by an inserter 642 into the processed video after processing.Removal and insertion of watermarks may require enablement by enablingdata. That data may be stored and/or generated in the processing system648 by a controller 638, and/or retrieved from a database 636 via asecure datalink 634. The datalink 634 may include the internet. Theenabling data preferably includes UMIDs for the watermarks insertedafter processing.

[0025] In a preferred embodiment, the enabling data includes encryptionkeys for removing and inserting encrypted watermarks.

[0026] The database 636 may store data for verifying the provenance ofinput material by checking the watermark against verification data whichmay be a UMID if the watermark comprises a UMID. The processor 646 maybe disabled by the control 630 in the presence of material which failsverification. For example, the control 638 checks the authenticity ofthe material received at input 632. Preferably, if the authenticitycheck indicates that the received material is not authentic, theprocessor 646 is disabled. The data for verifying authenticity ispreferably derived from the database 636.

[0027] The database 636 or another database (not shown) linked to it maystore metadata relating to the video material. Examples of metadata aregiven in the section Metadata below.

[0028] The watermark inserter 642 may reinsert the input watermark inthe processed video. Alternatively the inserter 642 may insert, into theprocessed video, a watermark different to that of the input watermark.For example, if the processor 646 is a mixer, and the watermark is aUMID, the processed video is effectively new material to which a newUMID is associated. Thus the inserter will usually insert a UMIDdifferent to the input UMID. The new UMID is preferably stored in thedatabase 636 to link the processed material to its metadata.

[0029] UMIDs-FIGS. 2 and 3.

[0030] UMIDs A UMID is described in SMPTE Journal March 2000. Referringto FIG. 2, an extended UMID is shown. It comprises a first set of 32bytes of basic UMID and a second set of 32 bytes of signature metadata.

[0031] The first set of 32 bytes is the basic UMID. The components are:

[0032] A 12-byte Universal Label to identify this as a SMPTE UMID. Itdefines the type of material which the UMID identifies and also definesthe methods by which the globally unique Material and locally uniqueInstance numbers are created.

[0033] A 1-byte length value to define the length of the remaining partof the UMID.

[0034] A 3-byte Instance number which is used to distinguish betweendifferent ‘instances’ of material with the same Material number.

[0035] A 16-byte Material number which is used to identify each clip.Each Material number is the same for related instances of the samematerial.

[0036] The second set of 32 bytes of the signature metadata as a set ofpacked metadata items used to create an extended UMID. The extended UMIDcomprises the basic UMID followed immediately by signature metadatawhich comprises:

[0037] An 8-byte time/date code identifying the time and date of theContent Unit creation.

[0038] A 12-byte value which defines the spatial co-ordinates at thetime of Content Unit creation.

[0039] 3 groups of 4-byte codes which register the country, organisationand user codes.

[0040] Each component of the basic and extended UMIDs will now bedefined in turn.

[0041] The 12-Byte Universal Label

[0042] The first 12 bytes of the UMID provide identification of the UMIDby the registered string value defined in table 1. TABLE 1 Specificationof the UMID Universal Label Byte No. Description Value (hex) 1 ObjectIdentifier 06h 2 Label size 0Ch 3 Designation: ISO 2Bh 4 Designation:SMPTE 34h 5 Registry: Dictionaries 01h 6 Registry: Metadata Dictionaries01h 7 Standard: Dictionary Number 01h 8 Version number 01h 9 Class:Identification and location 01h 10 Sub-class: Globally UniqueIdentifiers 01h 11 Type: UMID (Picture, Audio, Data, Group) 01, 02, 03,04h 12 Type: Number creation method XXh

[0043] The hex values in table 1 may be changed: the values given areexamples. Also the bytes 1-12 may have designations other than thoseshown by way of example in the table. Referring to the Table 1, in theexample shown byte 4 indicates that bytes 5-12 relate to a data formatagreed by SMPTE. Byte 5 indicates that bytes 6 to 10 relate to“dictionary” data. Byte 6 indicates that such data is “metadata” definedby bytes 7 to 10. Byte 7 indicates the part of the dictionary containingmetadata defined by bytes 9 and 10. Byte 10 indicates the version of thedictionary. Byte 9 indicates the class of data and Byte 10 indicates aparticular item in the class.

[0044] In the present embodiment bytes 1 to 10 have fixed preassignedvalues. Byte 11 is variable. Thus referring to FIG. 3, and to Table 1above, it will be noted that the bytes 1 to 10 of the label of the UMIDare fixed. Therefore they may be replaced by a 1 byte ‘Type’ code Trepresenting the bytes 1 to 10. The type code T is followed by a lengthcode L. That is followed by 2 bytes, one of which is byte 11 of Table 1and the other of which is byte 12 of Table 1, an instance number (3bytes) and a material number (16 bytes). Optionally the material numbermay be followed by the signature metadata of the extended UMID and/orother metadata.

[0045] The UMID type (byte 11) has 4 separate values to identify each of4 different data types as follows:

[0046] ‘01h’=UMID for Picture material

[0047] ‘02h’=UMID for Audio material

[0048] ‘03h’=UMID for Data material

[0049] ‘04h’=UMID for Group material (i.e. a combination of relatedessence).

[0050] The last (12th) byte of the 12 byte label identifies the methodsby which the material and instance numbers are created. This byte isdivided into top and bottom nibbles where the top nibble defines themethod of Material number creation and the bottom nibble defines themethod of Instance number creation.

[0051] Length

[0052] The Length is a 1-byte number with the value ‘13h’ for basicUMIDs and ‘33h’ for extended UMIDs.

[0053] Instance Number

[0054] The Instance number is a unique 3-byte number which is created byone of several means defined by the standard. It provides the linkbetween a particular ‘instance’ of a clip and externally associatedmetadata. Without this instance number, all material could be linked toany instance of the material and its associated metadata.

[0055] The creation of a new clip requires the creation of a newMaterial number together with a zero Instance number. Therefore, anon-zero Instance number indicates that the associated clip is not thesource material. An Instance number is primarily used to identifyassociated metadata related to any particular instance of a clip.

[0056] Material Number

[0057] The 16-byte Material number is a non-zero number created by oneof several means identified in the standard. The number is dependent ona 6-byte registered port ID number, time and a random number generator.

[0058] Signature Metadata

[0059] Any component from the signature metadata may be null-filledwhere no meaningful value can be entered. Any null-filled component iswholly null-filled to clearly indicate a downstream decoder that thecomponent is not valid.

[0060] The Time-Date Format

[0061] The date-time format is 8 bytes where the first 4 bytes are a UTC(Universal Time Code) based time component. The time is defined eitherby an AES3 32-bit audio sample clock or SMPTE 12M depending on theessence type.

[0062] The second 4 bytes define the date based on the Modified JulianData (MJD) as defined in SMPTE 309M. This counts up to 999,999 daysafter midnight on Nov. 17, 1858 and allows dates to the year 4597.

[0063] The Spatial Co-ordinate Format

[0064] The spatial co-ordinate value consists of three componentsdefined as follows:

[0065] Altitude: 8 decimal numbers specifying up to 99,999,999 meters.

[0066] Longitude: 8 decimal numbers specifying East/West 180.00000degrees (5 decimal places active).

[0067] Latitude: 8 decimal numbers specifying North/South 90.00000degrees (5 decimal places active).

[0068] The Altitude value is expressed as a value in meters from thecentre of the earth thus allowing altitudes below the sea level.

[0069] It should be noted that although spatial co-ordinates are staticfor most clips, this is not true for all cases. Material captured from amoving source such as a camera mounted on a vehicle may show changingspatial co-ordinate values.

[0070] Country Code

[0071] The Country code is an abbreviated 4-byte alpha-numeric stringaccording to the set defined in ISO 3166. Countries which are notregistered can obtain a registered alpha-numeric string from the SMPTERegistration Authority.

[0072] Organisation Code

[0073] The Organisation code is an abbreviated 4-byte alpha-numericstring registered with SMPTE. Organisation codes have meaning only inrelation to their registered Country code so that Organisation codes canhave the same value in different countries.

[0074] User Code

[0075] The User code is a 4-byte alpha-numeric string assigned locallyby each organisation and is not globally registered. User codes aredefined in relation to their registered Organisation and Country codesso that User codes may have the same value in different organisationsand countries.

[0076] Freelance Operators

[0077] Freelance operators may use their country of domicile for thecountry code and use the Organisation and User codes concatenated toe.g. an 8 byte code which can be registered with SMPTE. These freelancecodes may start with the ‘˜’ symbol (ISO 8859 character number 7Eh) andfollowed by a registered 7 digit alphanumeric string.

[0078] It will be noted from the foregoing discussion that a UMID may beused to identify not only video material, but also audio material, datamaterial, and a group of material.

[0079] Metadata-FIG. 4

[0080] The following is provided, by way of example, to illustrate thepossible types of metadata generated during the production of aprogramme, and one possible organisational approach to structuring thatmetadata in a database such as 636 in FIG. 1. A UMID embedded in videoas a watermark acts as an identifier which links the video with theassociated metadata in the database.

[0081]FIG. 4 illustrates an example structure for organising metadata. Anumber of tables each comprising a number of fields containing metadataare provided. The tables may be associated with each other by way ofcommon fields within the respective tables, thereby providing arelational structure. Also, the structure may comprise a number ofinstances of the same table to represent multiple instances of theobject that the table may represent. The fields may be formatted in apredetermined manner. The size of the fields may also be predetermined.Example sizes include “Int” which represents 2 bytes, “Long Int” whichrepresents 4 bytes and “Double” which represents 8 bytes. Alternatively,the size of the fields may be defined with reference to the number ofcharacters to be held within the field such as, for example, 8, 10, 16,32, 128, and 255 characters.

[0082] Turning to the structure in more detail, there is provided aProgramme Table. The Programme Table comprises a number of fieldsincluding Programme ID (PID), Title, Working Title, Genre ID, Synopsis,Aspect Ratio, Director ID and Picturestamp. Associated with theProgramme Table is a Genre Table, a Keywords Table, a Script Table, aPeople Table, a Schedule Table and a plurality of Media Object Tables.

[0083] The Genre Table comprises a number of fields including Genre ID,which is associated with the Genre ID field of the Programme Table, andGenre Description.

[0084] The Keywords Table comprises a number of fields includingProgramme ID, which is associated with the Programme ID field of theProgramme Table, Keyword ID and Keyword.

[0085] The Script Table comprises a number of fields including ScriptID, Script Name, Script Type, Document Format, Path, Creation Date,Original Author, Version, Last Modified, Modified By, PID associatedwith Programme ID and Notes. The People Table comprises a number offields including Image.

[0086] The People Table is associated with a number of Individual Tablesand a number of Group Tables. Each Individual Table comprises a numberof fields including Image. Each Group Table comprises a number of fieldsincluding Image. Each Individual Table is associated with either aProduction Staff Table or a Cast Table.

[0087] The Production Staff Table comprises a number of fields includingProduction Staff ID, Surname, Firstname, Contract ID, Agent, Agency ID,E-mail, Address, Phone Number, Role ID, Notes, Allergies, DOB, NationalInsurance Number and Bank ID and Picture Stamp.

[0088] The Cast Table comprises a number of fields including Cast ID,Surname, Firstname, Character Name, Contract ID, Agent, Agency ID,Equity Number, E-mail, Address, Phone Number, DOB and Bank ID andPicture Stamp. Associated with the Production Staff Table and Cast Tableare a Bank Details Table and an Agency Table.

[0089] The Bank Details Table comprises a number of fields includingBank ID, which is associated with the Bank ID field of the ProductionStaff Table and the Bank ID field of the Cast Table, Sort Code, AccountNumber and Account Name.

[0090] The Agency Table comprises a number of fields including AgencyID, which is associated with the Agency ID field of the Production StaffTable and the Agency ID field of the Cast Table, Name, Address, PhoneNumber, Web Site and E-mail and a Picture Stamp. Also associated withthe Production Staff Table is a Role Table.

[0091] The Role Table comprises a number of fields including Role ID,which is associated with the Role ID field of the Production StaffTable, Function and Notes and a Picture Stamp. Each Group Table isassociated with an Organisation Table.

[0092] The Organisation Table comprises a number fields includingOrganisation ID, Name, Type, Address, Contract ID, Contact Name, ContactPhone Number and Web Site and a Picture Stamp.

[0093] Each Media Object Table comprises a number of fields includingMedia Object ID, Name, Description, Picturestamp, PID, Format, scheduleID, script ID and Master ID. Associated with each Media Object Table isthe People Table, a Master Table, a Schedule Table, a Storyboard Table,a script table and a number of Shot Tables.

[0094] The Master Table comprises a number of fields including MasterID, which is associated with the Master ID field of the Media ObjectTable, Title, Basic UMID, EDL ID, Tape ID and Duration and a PictureStamp.

[0095] The Schedule Table comprises a number of fields includingSchedule ID, Schedule Name, Document Format, Path, Creation Date,Original Author, Start Date, End Date, Version, Last Modified, ModifiedBy and Notes and PID which is associated with the programme ID.

[0096] The contract table contains: a contract ID which is associatedwith the contract ID of the Production staff, cast, and organisationtables; commencement date, rate, job title, expiry date and details.

[0097] The Storyboard Table comprises a number of fields includingStoryboard ID, which is associated with the Storyboard ID of the shotTable, Description, Author, Path and Media ID.

[0098] Each Shot Table comprises a number of fields including Shot ID,PID, Media ID, Title, Location ID, Notes, Picturestamp, script ID,schedule ID, and description. Associated with each Shot Table is thePeople Table, the Schedule Table, script table, a Location Table and anumber of Take Tables.

[0099] The Location Table comprises a number of fields includingLocation ID, which is associated with the Location ID field of the ShotTable, GPS, Address, Description, Name, Cost Per Hour, Directions,Contact Name, Contact Address and Contact Phone Number and a PictureStamp.

[0100] Each Take Table comprises a number of fields including BasicUMID, Take Number, Shot ID, Media ID, Timecode IN, Timecode OUT, SignMetadata, Tape ID, Camera ID, Head Hours, Videographer, IN Stamp, OUTStamp. Lens ID, AUTOID ingest ID and Notes. Associated with each TakeTable is a Tape Table, a Task Table, a Camera Table, a lens table, aningest table and a number of Take Annotation Tables.

[0101] The Ingest table contains an Ingest ID which is associated withthe Ingest Id in the take table and a description.

[0102] The Tape Table comprises a number of fields including Tape ID,which is associated with the Tape ID field of the Take Table, PID,Format, Max Duration, First Usage, Max Erasures, Current Erasure, ETA(estimated time of arrival) and Last Erasure Date and a Picture Stamp.

[0103] The Task Table comprises a number of fields including Task ID,PID, Media ID, Shot ID, which are associated with the Media ID and ShotID fields respectively of the Take Table, Title, Task Notes,Distribution List and CC List. Associated with the Task Table is aPlanned Shot Table.

[0104] The Planned Shot Table comprises a number of fields includingPlanned Shot ID, PID, Media ID, Shot ID, which are associated with thePID, Media ID and Shot ID respectively of the Task Table, Director, ShotTitle, Location, Notes, Description, Videographer, Due date, Programmetitle, media title Aspect Ratio and Format.

[0105] The Camera Table comprises a number of fields including CameraID, which is associated with the Camera ID field of the Take Table,Manufacturer, Model, Format, Serial Number, Head Hours, Lens ID, Notes,Contact Name, Contact Address and Contact Phone Number and a PictureStamp.

[0106] The Lens Table comprises a number of fields including Lens ID,which is associated with the Lens ID field of the Take Table,Manufacturer, Model, Serial Number, Contact Name, Contact Address andContact Phone Number and a Picture Stamp.

[0107] Each Take Annotation Table comprises a number of fields includingTake Annotation ID, Basic UMID, Timecode, Shutter Speed, Iris, Zoom,Gamma, Shot Marker ID, Filter Wheel, Detail and Gain. Associated witheach Take Annotation Table is a Shot Marker Table.

[0108] The Shot Marker Table comprises a number of fields including ShotMarker ID, which is associated with the Shot Marker ID of the TakeAnnotation Table, and Description.

[0109] Watermarks-FIGS. 5 and 6

[0110] There is an ever increasing amount of information, andparticularly video, being recorded, stored and distributed digitally.The ease with which this information may be duplicated is a concern,since any copyrights in the underlying works may potentially be easilyinfringed by unauthorised copying. Accordingly, copyright owners may beunwilling to make available and distribute their works without adequateprotection against copying, or without being able to demonstrate that aparticular example of work originates from them and may be an infringingunauthorised copy.

[0111] One possible technique which seeks to provide a solution to thisproblem is digital watermarking. Digital watermarking allows a code tobe embedded in a digital work which contains information which may, forexample, identify the owner, the distributor and/or an authorisationcode. The digital watermark may be used in conjunction with otherdeterrents such as encryption.

[0112] The digital watermark, hereinafter referred to as the watermark,should be unique such that it, for example, unambiguously identifies theowner, the distributor and/or provides an authorisation code, atechnique often referred to a fingerprinting. Also, the watermark mayitself be a digital work such as an image, audio or video. The watermarkmay also contain an indication of whether the work may be copied freely,not copied at all or copied a predetermined number of times.

[0113] Preferably, the watermark should be undetectable, unalterable andnon-removable by unauthorised individuals. Also, the watermark shouldnot adversely degrade the underlying work in a manner that is readilyperceptible. However, the watermark should be readily discernible byauthorised individuals such that the owner and/or distributor may beidentified.

[0114] The watermark should be easily embedded into the underlyingdigital work. Preferably, the embedding technique should be such thatthat this can be easily performed during recording, thereby watermarkingthe work at source, and thus minimising the possibility of anynon-watermarked works being available.

[0115] The watermark may be placed in, for example, a header or label ofa digital work, or the watermark may be embedded within the data fieldsof the digital work itself. Preferably, the watermark is reproduced manytimes within a work and, more preferably, is present in every frame ofthe digital work. Alternatively, the watermark may be placed directlyonto the media which carries the digital work.

[0116] The watermark may be robust such that it may not be removed ordegraded by individuals seeking to make unauthorised copies.Unauthorised attempts to remove the robust watermark should result insevere degradation of the data, rendering the data useless. Situationswhere the data contains much redundant information, such as in video,may render the robust watermark susceptible to attack by, for example,frame dropping or the like. Hence, the robust watermark shouldpreferably withstand such attacks and may, for example, change fromframe to frame and may utilise any error correction/recovery techniqueswhich are applied to data.

[0117] Alternatively, the watermark may be fragile such that it isdamaged should an unauthorised copy be made.

[0118] However, the watermark should also preferably be reversible andremovable by the owner, if required. Removal may be particularly usefulduring, for example, a post-production stage to reduce any cumulativeeffects of the watermark on the underlying work. Also, where informationfrom different sources are edited together it may be desired that adifferent watermark is applied to the edited product.

[0119] End-user equipment may be configured to recognise the watermarksuch that it will not allow copying of protected works. Alternatively,the equipment may be configured such that it will operate only withworks originating from a particular owner, distributed through aparticular distributor or where the work contains a particularauthorisation code.

[0120] The watermark may be extracted by comparing watermarked withnon-watermarked data and its authenticity established.

[0121] Two techniques for embedding a watermark within the data fieldsof a digital work will now be described in more detail. The first is toembed the watermark in the spatial domain, the second is to embed thewatermark in the frequency domain. Both of these embedding processesshould be such that they do not result in a significant degradation ofthe data being watermarked.

[0122] Spatial Domain Watermarks

[0123] The process, in overview, involves altering predetermined databits with the bits of a watermark to produce watermarked data. Theexistence of watermark may be determined by performing the reverseoperation on the watermarked data.

[0124] One approach is to embed a watermark by substitutinginsignificant bits of pseudo-randomly selected data with bitsrepresenting the watermark. However, these watermarks are susceptible todestruction by processing the least significant bits of the data.Another is to insert geometric patterns into the data which represent awatermark. However, these watermarks are susceptible to destruction bygeometric processing of the data. A further approach is to embed awatermark in a manner which resembles quantisation noise as describedwith reference to FIG. 5 below and more fully described in articlestitled “Embedding Secret Information into a Dithered Multi-Level Image”by K Tanaka et al, IEEE Military Communications Conference pages216-220, 1990 and “Video Steganography” by K Mitsui, IMA IntellectualProperty Proceedings, volume 1, pages 187-296, 1994. However, thesewatermarks are susceptible to destruction by signal processing,particularly by requantisation of the data.

[0125] Referring now to FIG. 5, a source 650 produces a digital datasignal 652, such as digital video. A watermark inserter 700 is coupledto the source 650 and receives the digital data signal 652. Thewatermark inserter 700 applies the watermark 663 by applying thewatermark to the digital data signal 652 in a manner that resemblesrequantisation noise to produce watermarked data 705. A storage device670 is coupled to the watermark inserter 700 and stores the watermarkeddata 705.

[0126] A yet further approach is to randomly select n pairs of imagepoints (a_(i), b_(i)) and increase the brightness of a_(i) by one whiledecreasing the brightness of b_(i) by one. Assuming certain statisticalproperties of the image are satisfied, the sum of the differences of then pairs of points will be 2n.

[0127] Alternatively, where the data signal comprises at least twocomponents (for example [Y, U, V] according to MPEG, PAL or NTC), thewatermark may be embedded by assigning values to these components which,in combination, do not usually occur. Also, where a watermark is to beembedded in, for example, video data containing two image fields, apositive watermark may be placed into the first field and a negativewatermark into the second field. When watermarked image fields areplayed there is a masking effect due to the interlacing of the fieldsand the visual perception of the watermark is significantly reduced.

[0128] Frequency Domain Watermarks

[0129] The process, in overview, involves obtaining a frequency spectralimage of the data to which the watermark is to be applied. The watermarkis embedded into predetermined components of the of the frequencyspectral image. Thereafter, the watermarked frequency spectral image issubjected to an inverse transform to produce watermarked data. Thewatermark may be extracted by performing the reverse operation on thewatermarked data.

[0130] Alternatively, the watermark may be encoded by adjusting everyfrequency coefficient by a small amount as more fully described inEuropean Patent Application 0 766 468, NEC Corporation. This has theadvantage of making the watermark less sensitive to damage, butincreases overall noise levels.

[0131] Referring now to FIG. 6, a source 650 produces a digital datasignal 652, such as digital video. A frequency transformer 655 iscoupled to the source 650 and receives the digital data signal 652. Thefrequency transformer 655 transforms the digital data signal 652 intofrequency domain data 657 using, for example, Discrete CosineTransforms. A watermark inserter 660 is coupled to the frequencytransformer and receives the frequency domain data 657. The data ispartitioned into blocks and the Discrete Cosine Transform (DCT) of eachof these blocks is computed. Thereafter, the frequency coefficients ofthe blocks are adjusted. A pseudo random subset of blocks is chosen and,in each such block, coefficients of a predetermined subset offrequencies adjusted such that their relative values encode a data bit.The variance in the relative values and the selection of thepredetermined subset of frequencies should be such that the watermark isnot perceptible. This watermark is sensitive to damage by noise orfurther processing, whereby it may be removed.

[0132] The pseudo-random subset of blocks is selected according to a keystored in the database 636 or generated in the control 638. The data tobe embedded is preferably a UMID or an identifier having fewer bits thana UMID but which links to a UMID.

[0133] An inverse frequency transformer 665 converts the thuswatermarked frequency domain data to spatial domain data. A storagedevice 670 may store the watermarked data produced by the inversetransformer 665.

[0134] The system of FIG. 6 is used to produce the watermarked videoinput at 632 to the remover 640 of FIG. 1.

[0135] The system of FIG. 6 is also used as the inserter 642 of FIG. 1.

[0136]FIG. 7 shows an example of the remover of FIG. 1, for removingwatermarks produced by the inserter of FIG. 6.

[0137] A transformer 656 receives the watermarked video and transformsit using a Discrete Cosine Transform.

[0138] The database 636 or the generator 638 provides the key by whichthe pseudo random subset of blocks is selected by a remover and decoder658. The remover/decoder 658 decodes the watermark data from theselected blocks.

[0139] The remover/decoder then applies a process to the selected blockwhich effectively removes the watermark, e.g. by adding noise preferablyso as to not significantly degrade the video.

[0140] The decoded data is provided to a verifier V which authenticatesthe data, e.g. by comparing it with data stored in the database 636. Ifthe authentication fails, the processor 646 of FIG. 1 may be disabled.

[0141] An inverse transforms receives the frequency domain data from theremover/decoder 658 and inverse transforms it to spatial domain data.

[0142] Modifications

[0143] It will be appreciated that the data is digital data in theforegoing embodiments. Thus the invention may be implemented usingprogrammable digital signal processors. Thus the invention may beembodied in software, and stored in recording media.

[0144] Although for convenience the foregoing describes videoprocessing, the invention may be applied to audio processing. UMIDs arelong e.g. 32 or 64 bytes. The material may be identified by anidentifier, in the material, and which has fewer bits than a UMID butwhich links the material to a UMID which uniquely identifies thematerial.

[0145] Whilst the foregoing description illustrates the invention byreference to video material, the invention may be applied to any one ormore of video material, audio material, and data material.

[0146] It wil be appreciated that other watermarking techniques may beused and that other ways of removing watermarks may be used. Inprinciple, a watermark may be removed by applying a process which is theinverse of the embedding process thus providing in principle preciseremoval.

1. A material processing system for processing material including awatermark, the system comprising a remover for removing the watermark, aprocessor for processing the material from which the watermark has beenremoved, and an inserter for inserting a watermark into the processedmaterial.
 2. A system according to claim 1, wherein the processor has auser interface for controlling the processes performed thereby.
 3. Asystem according to claim 2, wherein the remover and the inserter arearranged to operate automatically and independently of the user.
 4. Asystem according to claim 1, 2, or 3, further comprising a databaseprocessor linked to the remover, the database processor containing dataenabling the removal of the watermark from the material to be processed.5. A system according to claim 1, 2 or 3, further comprising a databaseprocessor linked to the inserter, the database processor containing dataenabling insertion of the watermark into the processed material.
 6. Asystem according to claim 4 or 5, wherein the said enabling dataincludes an encryption key.
 7. A system according to claim 4, 5 or 6,wherein the inserter and the remover are linked to the databaseprocessor by a communications link.
 8. A system according to claim 7,wherein the communications link includes the internet.
 9. A systemaccording to any preceding claims arranged to check the authenticity ofthe said material including the reversible watermark.
 10. A systemaccording to claim 9, arranged to disable the said processor if thematerial fails the authenticity check.
 11. A method of processingmaterial including a watermark, comprising the steps of: removing thewatermark; processing the material from which the watermark has beenremoved using a processor; and inserting a watermark into the processedmaterial.
 12. A method according to claim 11, wherein the steps ofremoving and inserting are automatic and independent of a user of theprocessor.
 13. A method according to claim 12, wherein the removal andinsertion are hidden from the user.
 14. A method according to claim 11,12 or 13, further comprising retrieving from a database data enablingthe removal of the watermark included in the material to be processed.15. A method according to claim 11, 12 or 13, further comprisingretrieving from a database data enabling the insertion of a watermarkinto the processed material.
 16. A method according to claim 14 or 15,wherein the said enabling data includes an encryption key.
 17. A methodaccording to claim 14, 15 or 16, wherein the enabling data is retrievedvia a communications link.
 18. A method according to claim 17, whereinthe communications link includes the internet.
 19. A method according toany one of claims 11 to 18, comprising the steps of checking theauthenticity of the said material including the reversible watermark.20. A method according to claim 19, comprising the steps of disablingthe processing of the material if the material fails the authenticitycheck.
 21. A method of removing data embedded in material comprising thesteps of: receiving material in which data is embedded; accessing aninformation store storing information enabling the data to be removed;and removing the said data using the enabling data accessed from thestore.
 22. A method comprising the steps of: embedding data in material;and storing, in an information store, information for enabling the datato be removed from the material.
 23. Apparatus for removing dataembedded in material comprising: an input for receiving material inwhich data is embedded; an information store for storing informationenabling the data to be removed; and a remover arranged to remove thesaid data using the enabling data accessed from the store.
 24. Apparatuscomprising: an embedder for embedding data in material; a store forstoring information for enabling the data to be removed from thematerial.
 25. Apparatus according to claim 23 further comprising agenerator for generating the enabling information.
 26. Apparatus ormethod according to any preceding claim, wherein the material is one ormore of video material, audio material and data material.
 27. A computerprogram product arranged to carry out the method of any one of claims 11to 22 when run on a programmable digital signal processor.
 28. A storagemedium storing a computer program product according to claim
 27. 29. Amethod of processing material substantially as hereinbefore describedwith reference to FIG. 1 optionally as modified by: FIGS. 2 and 3; FIG.4, FIG. 5; and/or FIGS. 6 and 7 of the accompanying drawings. 30.Apparatus for processing material substantially as hereinbeforedescribed with reference to FIG. 1 optionally as modified by: FIGS. 2and 3; FIG. 4, FIG. 5; and/or FIGS. 6 and 7 of the accompanyingdrawings.